Using LFE+Main resulted in better FR - need help interpreting the results

[CK.]

Hello everyone,

Hope you are doing alright.

I need your expert opinion please.

My Setup:
Avr: denon 3700h
F: KEF R3
C: KEF R6
S: KEF Q150
SW: Rel 1003 HT MKii, connects to AVR SW out only via LFE channel.

Initial Settings

Mode: LFE@120Hz
XO: 100Hz for all speakers
Speakers: "Small"
SW XO knob: turn to max (200Hz)
SW Gain knob: 40%
AVR Sub level: -7 (lowest it can go is -12)


The story

I noticed my sub was rolling off quite a bit below 40Hz (see photo-1, L+R) no matter the position, so I contacted REL who suggested that I use their approach and set speakers to LARGE, LFE+Main, XO on avr to 250Hz and set the actual XO on the sub.

At which point I told them that this is against all the advise I have been given by all other enthusiasts in various forums and blogs but they insisted I give it a try.

So long story short, without changing the position of the sub I changed the settings as follows:


New Settings

Mode: LFE+Main@120Hz
XO: 200Hz
Speakers: "LARGE" for all speakers
SW XO knob: 100 Hz
SW Gain knob: 70%

Attached you can see the comparison (photo-2), blue line is the new settings REL suggested.


Questions

1. There seems to be an improvement especially below 40Hz, would you recommend keeping the new settings?
2. How do you interpret the results? Did I got lucky ?
3. Does the FR draw the full picture or do I need to look at other metrics as well?

Many thanks to all have a Happy New Year!

 

[DVDdoug]

There seems to be an improvement especially below 40Hz, would you recommend keeping the new settings?

Of course, use whatever sounds better.

Normally "large" means that the sub is ONLY used for the "point one" LFE channel and all of the bass from the other channels goes to your main speakers. (So the sub is not used with regular stereo music.)

XO: 200Hz
Speakers: "LARGE" for all speakers
SW XO knob: 100 Hz

I don't know what's happening with two different crossover frequencies...

 

[CK.]

Of course, use whatever sounds better.

Normally "large" means that the sub is ONLY used for the "point one" LFE channel and all of the bass from the other channels goes to your main speakers. (So the sub is not used with regular stereo music.)


I don't know what's happening with two different crossover frequencies...

Hey, thanks for your reply! Yeah large means that but when you also set the mode to "LFE+Main" it also sends bass information to speakers and this is where it gets a bit tricky. Do you want your speakers to play that low even if they can or is it more efficient and better to send all bass freq to the sub even if the first method yields a better low frequency extension below 40Hz? Do you compromise mid-range clarity/performance if you also sent the bass freq to the mains?

Frequency response maybe a bit better but is that all there is to it? I do not have a "trained" ear and have not listened to a system that is "reference" so how can I answer that?

 

[Thomas_A]

Do you use the R3 sealed? They need to be rolling off at 12 dB/octave, if you are using the AVR crossover.

 

[CK.]

Do you use the R3 sealed? They need to be rolling off at 12 dB/octave, if you are using the AVR crossover.

No they are not sealed, about 50cm from the back wall. not sure I understand what you mean by that statement, how do I take that into account?

 

[OCA]

Hello everyone,

Hope you are doing alright.

I need your expert opinion please.

My Setup:
Avr: denon 3700h
F: KEF R3
C: KEF R6
S: KEF Q150
SW: Rel 1003 HT MKii, connects to AVR SW out only via LFE channel.

Initial Settings

Mode: LFE@120Hz
XO: 100Hz for all speakers
Speakers: "Small"
SW XO knob: turn to max (200Hz)
SW Gain knob: 40%
AVR Sub level: -7 (lowest it can go is -12)


The story

I noticed my sub was rolling off quite a bit below 40Hz (see photo-1, L+R) no matter the position, so I contacted REL who suggested that I use their approach and set speakers to LARGE, LFE+Main, XO on avr to 250Hz and set the actual XO on the sub.

At which point I told them that this is against all the advise I have been given by all other enthusiasts in various forums and blogs but they insisted I give it a try.

So long story short, without changing the position of the sub I changed the settings as follows:


New Settings

Mode: LFE+Main@120Hz
XO: 200Hz
Speakers: "LARGE" for all speakers
SW XO knob: 100 Hz
SW Gain knob: 70%

Attached you can see the comparison (photo-2), blue line is the new settings REL suggested.


Questions

1. There seems to be an improvement especially below 40Hz, would you recommend keeping the new settings?
2. How do you interpret the results? Did I got lucky ?
3. Does the FR draw the full picture or do I need to look at other metrics as well?

Many thanks to all have a Happy New Year!

Where did Audyssey crossover your sub with autocalibration?

 

[Thomas_A]

No they are not sealed, about 50cm from the back wall. not sure I understand what you mean by that statement, how do I take that into account?

Normally the cross-over from the AVR is 12 dB/octave for the mains and 24 dB/octave for the subs. If you disable the sub x-over (or put it very high), you must match the roll-off of the mains with the sub. A closed box rolls off with 12 dB/octave, so adding 12 dB/octave with the AVR will give you 24 dB/octave, thus matching the low-pass of the AVR/sub x-over (24 dB/octave).

I looked at the R3 meta roll-off here (ported vs. sealed). X-over should be around 80-90 Hz with sealed enclosure. Ported, well I believe you get som interference around 40 Hz, since it has a hump there.

KEF R3 Meta - Review & Measurements by Erin

https://www.erinsaudiocorner.com/loudspeakers/kef_r3_meta/

www.audiosciencereview.com

 

[CK.]

Where did Audyssey crossover your sub with autocalibration?

Sub at 40Hz and main speakers at 30Hz....:

 

[CK.]

Normally the cross-over from the AVR is 12 dB/octave for the mains and 24 dB/octave for the subs. If you disable the sub x-over (or put it very high), you must match the roll-off of the mains with the sub. A closed box rolls off with 12 dB/octave, so adding 12 dB/octave with the AVR will give you 24 dB/octave, thus matching the low-pass of the AVR/sub x-over (24 dB/octave).

I looked at the R3 meta roll-off here (ported vs. sealed). X-over should be around 80-90 Hz with sealed enclosure. Ported, well I believe you get som interference around 40 Hz, since it has a hump there.

KEF R3 Meta - Review & Measurements by Erin

https://www.erinsaudiocorner.com/loudspeakers/kef_r3_meta/

www.audiosciencereview.com

Thanks for the explanation, I sort of get what you are saying but what I dont understand is that on the AVR there only one XO. The XO I am using (either on AVR or sub itself) is at 100Hz so way above what the mains are starting to roll-off (ported).

I am tempted to just go with the "common" way of setting the XO on the avr and the XO on the sub to very high and then boosting the sub by 3-4dB between 30-40Hz. For the sub the manufacturer states 24Hz at -6dB and I do not listen to levels above 80dB (-15 in avr).

My mains go deeper than my sub but my sub has a more linear response between 40-100Hz....

 

[OCA]

Sub at 40Hz and main speakers at 30Hz....:

Audyssey cannot crossover mains below 40Hz, it sets them as "Large" and doesn't crossover at all. Subwoofer's are not crossovered by definition. If you have MultEQ app and the original Audyssey measurement there (in ady format), I can check for you.

 

[CK.]

Audyssey cannot crossover mains below 40Hz, it sets them as "Large" and doesn't crossover at all. Subwoofer's are not crossovered by definition. If you have MultEQ app and the original Audyssey measurement there (in ady format), I can check for you.

Hello OCA,

Thanks for your feedback and for taking an interest. Want I meant to say was that audyssey assessed that my mains can play down (and thus be corrected) to 30Hz and sub down to 40Hz. Please see attached screenshots. I have MultiEQ-X for PC.

What is troubling to me is that in order to get a better performance below 40Hz it seems that I have to set my speakers to large (and set LFE+Main) in order to let my mains contribute in that range (below 40hz) since my sub is not able to. But this is something I would rather avoid because of many reasons as mentioned above.

thanks

 

[OCA]

Kef R3 spec -6 dB bass roll off is at 38 Hz while your REL sub's is at 24 Hz.

For best clarity, you want to crossover speakers at the nearest higher Audyssey slot to their spec bass roll off point i.e. 40Hz for the R3, 60Hz for R6/Q150. You also want to EQ them to their anechoic chamber (or spinorama) responses chosen as target curves for that matter.

"LFE+Main" should almost always be preferred to "LFE" otherwise each speaker is left on its own to produce bass signals (no crossovers for any speaker will be processed) and subwoofer will only produce ".1" LFE track during Dolby/DTS/Auro playback. You may see a flatter bass response at different crossover points but this is due to wrong subwoofer placement/alignment/polarity and you should fix that instead of changing spec crossover points. Audyssey's quite ancient method to select speaker crossover points is also quite prone to errors so should not be a firm reference to you.

I would also suggest bi-amping the R3s since you don't seem to be using height speakers and your AVR has the option to do so. These speakers have high impedance and loads below 50Hz and are not an easy feed for a multichannel. It should make a difference.

 

[Thomas_A]

Thanks for the explanation, I sort of get what you are saying but what I dont understand is that on the AVR there only one XO. The XO I am using (either on AVR or sub itself) is at 100Hz so way above what the mains are starting to roll-off (ported).

I am tempted to just go with the "common" way of setting the XO on the avr and the XO on the sub to very high and then boosting the sub by 3-4dB between 30-40Hz. For the sub the manufacturer states 24Hz at -6dB and I do not listen to levels above 80dB (-15 in avr).

My mains go deeper than my sub but my sub has a more linear response between 40-100Hz....

As mentioned the AVR x-over is meant to be used with sealed enclosures. See the link I gave to the R3 Meta. Plug the port and use AVR crossover at 80-90 Hz, sub crossover off or highest pos.

 

[CK.]

Kef R3 spec -6 dB bass roll off is at 38 Hz while your REL sub's is at 24 Hz.

For best clarity, you want to crossover speakers at the nearest higher Audyssey slot to their spec bass roll off point i.e. 40Hz for the R3, 60Hz for R6/Q150. You also want to EQ them to their anechoic chamber (or spinorama) responses chosen as target curves for that matter.

"LFE+Main" should almost always be preferred to "LFE" otherwise each speaker is left on its own to produce bass signals (no crossovers for any speaker will be processed) and subwoofer will only produce ".1" LFE track during Dolby/DTS/Auro playback. You may see a flatter bass response at different crossover points but this is due to wrong subwoofer placement/alignment/polarity and you should fix that instead of changing spec crossover points. Audyssey's quite ancient method to select speaker crossover points is also quite prone to errors so should not be a firm reference to you.

I would also suggest bi-amping the R3s since you don't seem to be using height speakers and your AVR has the option to do so. These speakers have high impedance and loads below 50Hz and are not an easy feed for a multichannel. It should make a difference.

Yeah I have used EQ based on the anechoic measurements and I would prefer to cross the the sub a bit lower as you said but unfortunately the sub is crossed higher in order to fill in certain dips in the response of the main speakers. I agree that it is best to fix that but the main speakers cannot be placed elsewhere so the alternative is to cross higher (100hz) and let the sub fill the gap (which it does).

Regarding LFE/LFE+Main, what you are describing holds true if you have your speakers set as "large" (full range), otherwise if you set them as small then all the frequencies below the XO are sent to the subwoofer (stereo and movies). It seems that the consensus is to use LFE with speakers set to small.
I agree audyssey can get the XO wrong.

Regarding bi-amping, I am not sure if my AVR has enough power to offer an audible improvement, many suggested that unless you have the top-tier denon avr it does not offer any advantage.
If you use the THX recommendation for an 80hz cross-over then you can avoid having the lower frequencies being played by the mains which as you said is quite taxing on the AVR.
But it all depends on the sub I guess, if your sub has a linear response below 80hz or even 100hz then why not let the sub reproduce these frequencies and not the mains? Yes the main may go lower but why not alleviate them?

 

[CK.]

As mentioned the AVR x-over is meant to be used with sealed enclosures. See the link I gave to the R3 Meta. Plug the port and use AVR crossover at 80-90 Hz, sub crossover off or highest pos.

Why do you say this, the majority of main speakers are not sealed and the AVR XO is always used (different XO can be implemented by the avr for each speaker separately in a multi-channel system based on the capabilities and placement). At a cross-over of 80-90 the main (ported) speakers will not be able to contribute below 40Hz anyway right? assuming you are not setting them as full-range.
As you said the roll-off of the AVR XO is 12dB/octave.

 

[Thomas_A]

Why do you say this, the majority of main speakers are not sealed and the AVR XO is always used (different XO can be implemented by the avr for each speaker separately in a multi-channel system based on the capabilities and placement). At a cross-over of 80-90 the main (ported) speakers will not be able to contribute below 40Hz anyway right? assuming you are not setting them as full-range.
As you said the roll-off of the AVR XO is 12dB/octave.

The standard slopes of the crossover in AVRs is 24 dB/octave for the low pass and 12 dB/octave for the high-pass. If your want both slopes to match at 24 dB/octave you need to have a 12 dB/octave acoustic slope of the mains ( or the center, or the surrounds). That is achieved with sealed enclosures. Again look at the slopes of the R3 sealed (blue line). It falls with 12 dB/octave with its -3 dB around 80-90 Hz. Adding 12 dB/octave filter from the AVR will yield 24 dB/octave slope with -6 dB around 80-90 Hz, which will be perfectly matched with a 24 dB/octave slope of the subwoofer.

 

[OCA]

Yeah I have used EQ based on the anechoic measurements and I would prefer to cross the the sub a bit lower as you said but unfortunately the sub is crossed higher in order to fill in certain dips in the response of the main speakers. I agree that it is best to fix that but the main speakers cannot be placed elsewhere so the alternative is to cross higher (100hz) and let the sub fill the gap (which it does).

Regarding LFE/LFE+Main, what you are describing holds true if you have your speakers set as "large" (full range), otherwise if you set them as small then all the frequencies below the XO are sent to the subwoofer (stereo and movies). It seems that the consensus is to use LFE with speakers set to small.
I agree audyssey can get the XO wrong.

Regarding bi-amping, I am not sure if my AVR has enough power to offer an audible improvement, many suggested that unless you have the top-tier denon avr it does not offer any advantage.
If you use the THX recommendation for an 80hz cross-over then you can avoid having the lower frequencies being played by the mains which as you said is quite taxing on the AVR.
But it all depends on the sub I guess, if your sub has a linear response below 80hz or even 100hz then why not let the sub reproduce these frequencies and not the mains? Yes the main may go lower but why not alleviate them?

Nothing I disagree with all of that

 

[CK.]

The standard slopes of the crossover in AVRs is 24 dB/octave for the low pass and 12 dB/octave for the high-pass. If your want both slopes to match at 24 dB/octave you need to have a 12 dB/octave acoustic slope of the mains ( or the center, or the surrounds). That is achieved with sealed enclosures. Again look at the slopes of the R3 sealed (blue line). It falls with 12 dB/octave with its -3 dB around 80-90 Hz. Adding 12 dB/octave filter from the AVR will yield 24 dB/octave slope with -6 dB around 80-90 Hz, which will be perfectly matched with a 24 dB/octave slope of the subwoofer.

Hm ok now I understand, that's interesting...also because this rarely comes up in discussions related to choosing the right cross-over. I will give it a try and let you know, thanks.